Monitoring prostate thermal therapy with diffusion-weighted MRI

Department of Electrical Engineering, Stanford University, Stanford, California 94305-5488, USA.
Magnetic Resonance in Medicine (Impact Factor: 3.4). 06/2008; 59(6):1365-72. DOI: 10.1002/mrm.21589
Source: PubMed

ABSTRACT For MR-guided minimally invasive therapies, it is important to have a repeatable and reliable tissue viability evaluation method. The use of diffusion-weighted MRI (DWI) to evaluate tissue damage was assessed in 19 canine prostates with cryoablation or high-intensity ultrasound (HIU) ablation. The apparent diffusion coefficient (ADC) trace value was measured in the treated tissue immediately upon the procedure and on the posttreatment follow-up. For the acute lesions, the ADC value decreased to (1.05+/-0.25)x10(-3) mm2/s, as compared to (1.64+/-0.24)x10(-3) mm2/s before the treatment. There was no statistical difference between previously frozen or previously ultrasound-heated lesions in terms of the 36% ADC reduction (P=0.66). The ADC decrease occurred early during the course of the treatment, which appears to complicate DWI-based thermometry. Over time, the ADC value increased as the tissue recovered and regenerated. This study shows that DWI could be a promising method to monitor prostate thermal therapies and to provide insight on tissue damage and tissue remodeling after injury.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Diffusion-weighted magnetic resonance (MR) imaging (DWI) is now widely incorporated as a standard MR imaging sequence for the assessment of the male pelvis. DWI can improve the detection, characterization, and staging of pelvic malignancies, such as prostate, bladder, and rectal cancers. There is growing interest in applying quantitative DWI for the assessment of tumor treatment response. In addition, the technique seems promising for the evaluation of metastatic nodal and bone disease in the pelvis.
    Radiologic Clinics of North America 11/2012; 50(6):1127-44. DOI:10.1016/j.rcl.2012.08.008 · 1.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic resonance imaging (MRI) and MR spectroscopic imaging (MRSI) have been gaining acceptance as tools in the evaluation of prostate cancer. We compared the accuracy of transrectal ultrasound (TRUS)-guided biopsy and dynamic contrast-enhanced MRI combined with three-dimensional (3D) MRSI in locating prostate tumours and determined the influence of prostate weight on MRI accuracy. Between March 1999 and October 2006, 507 patients with localised prostate cancer underwent radical prostatectomy (RP) at the Jules Bordet Institute. Of these, 220 had undergone endorectal MRI (1.5 T Siemens Quantum Symphony) and 3D-MRSI prior to RP. We retrospectively reviewed data on tumour location and compared the results obtained by MRI and by TRUS-guided biopsy with those obtained on histopathology of the RP specimen. Patient data were as follows: median age 62.4 years (45-74); median PSA 6.36 ng/ml (0.5-22.6); 73.6% of patients had non-palpable disease (T1c); median biopsy Gleason score 6 (3-9); median RP specimen weight 50 g (12-172); median pathological Gleason score 7 (4-10); 68.64% of patients had organ-confined (pT2) disease. Tumour localisation was correlated with RP data in a significantly higher percentage of patients when using MRI rather than TRUS-guided biopsy (47.4 vs. 36.6%, p < 0.0001). MRI was marginally superior to TRUS-guided biopsy in detecting malignancy at the prostate apex (48.3 vs. 41.9%, p = 0.0687) and somewhat better at the prostate base (46 vs. 39.1%, p = 0.0413). It was highly significantly better at mid-gland (52 vs. 41.1%, p = 0.0015) and in the transition zone (40.1 vs. 24.3%, p < 0.0001). MRI had higher sensitivity in larger (≥50 g) than smaller (<50 g) prostates (50.3 vs. 42.2%, p = 0.0017). MRI was superior to TRUS-guided biopsy in locating prostate tumours except at the gland apex. MRI was more accurate in larger (≥50 g) than smaller prostates.
    Urologia Internationalis 01/2012; 88(1):12-7. DOI:10.1159/000331909 · 1.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: There is currently a great deal of interest in the possible use of focal therapies for prostate cancer, since such treatments offer the prospect for control or cure of the primary disease with minimal side effects. Many forms of thermal therapy have been proposed for focal ablation of prostate cancer, including laser, high intensity ultrasound and cryotherapy. This review will demonstrate the important roles that magnetic resonance imaging (MRI) guidance can offer to such focal ablation, focusing on the use of high intensity ultrasonic applicators as an example of one promising technique. Transurethral and interstitial high intensity ultrasonic applicators, designed specifically for ablation of prostate tissue were tested extensively in vivo in a canine model. The roles of MRI in positioning the devices, monitoring prostate ablation, and depicting ablated tissue were assessed using appropriate MRI sequences. MRI guidance provides a very effective tool for the positioning of ablative devices in the prostate, and thermal monitoring successfully predicted ablation of prostate tissue when a threshold of 52ºC was achieved. Contrast enhanced MRI accurately depicted the distribution of ablated prostate tissue, which is resorbed at 30 days. Guidance of thermal therapies for focal ablation of prostate cancer will likely prove critically dependent on MRI functioning in four separate roles. Our studies indicate that in three roles: device positioning; thermal monitoring of prostate ablation; and depiction of ablated prostate tissue, MR techniques are highly accurate and likely to be of great benefit in focal prostate cancer ablation. A fourth critical role, identification of cancer within the gland for targeting of thermal therapy, is more problematic at present, but will likely become practical with further technological advances.
    The Canadian Journal of Urology 04/2013; 20(2):6672-81. · 0.91 Impact Factor


Available from